InSAR-based characterization of rock glacier movement in the Uinta Mountains, Utah, USA

Rock glaciers are a prominent component of many alpine landscapes and constitute a significant water resource in some arid mountain environments. Here, we employ satellite-based interferometric synthetic aperture radar (InSAR) between 2016 and 2019 to identify and monitor active and transitional rock glaciers in the Uinta Mountains (Utah, USA), an area of ~3,000 km2. We used mean velocity maps to generate an inventory for the Uinta Mountains containing 205 active and transitional rock glaciers. These rock glaciers are 11.9 ha in area on average and located at a mean elevation of 3308 m, where mean annual air temperature is -0.25 ˚C. The mean downslope velocity for the inventory is 1.94 cm/yr, but individual rock glaciers have LOS velocities ranging from 0.35 to 6.04 cm/yr. To search for relationships with climatic drivers, we investigated the time-dependent motion of three rock glaciers. We found that rock glacier motion has a significant seasonal component, with rates that are more than 5 times faster during the late summer compared to the rest of the year. Rock glacier velocities also appear to be correlated with the snow-water equivalent of the previous winter’s snowpack. Our results demonstrate the ability to use satellite InSAR to monitor rock glaciers over large areas and provide insight into the environmental factors that control their kinematics.岩冰川（rock glacier）是诸多山地景观的重要组成部分，在部分干旱山区环境中亦是关键的水资源储备。本研究采用2016至2019年的星载合成孔径雷达干涉测量（InSAR）技术，对美国犹他州犹因塔山脉（总面积约3000平方千米）内的活动型与过渡型岩冰川开展识别与动态监测工作。我们通过平均速度图生成了犹因塔山脉的岩冰川编目，共计收录205处活动型与过渡型岩冰川。这些岩冰川的平均面积为11.9公顷，平均分布海拔为3308米，该区域的年平均气温为-0.25℃。该编目内岩冰川的平均下坡流速为1.94厘米/年，但单处岩冰川的视线向（LOS）流速介于0.35至6.04厘米/年之间。为探究岩冰川运动与气候驱动因子间的关联，我们对3处岩冰川的时变运动特征进行了分析。研究结果显示，岩冰川运动存在显著的季节性变化：夏末时段的运动速率较其余时段高出5倍以上。岩冰川流速亦与前一冬季积雪的雪水当量（snow-water equivalent）呈显著相关关系。本研究证实了利用星载InSAR技术对大尺度区域内岩冰川进行监测的可行性，并为解析调控岩冰川运动学特征的环境因子提供了重要见解。